Abstract  Ambient air pollution has been associated with increased mortality and morbidity; however, few studies have examined the short-term effect of air pollution specifically on chronic obstructive pulmonary disease (COPD), which is an important cause of mortality and morbidity world wide. In this analysis, we examined the associations between daily air pollution levels [particulate matter less than 10 microns in aerodynamic diameter (PM10), sulfur dioxide (SO2) and nitrogen dioxide (NO2)] and COPD mortality in four Chinese cities. We used Poisson regression models with natural spline smoothing functions to adjust for long-term and seasonal trends of COPD mortality, as well as other time-varying covariates. We did a meta-analysis to obtain the 4-city average estimates. Air pollution (PM10, SO2, and NO2) was found to be associated with increased risk of COPD mortality in these four cities. Using the random-effects model, an increase of 10 mu g m(-3) of 2-day moving average concentrations of PM10, SO2 and NO2 corresponded to a 0.78% (95% CI, 0.13-1.42), 1.30% (95% CI, 0.61-1.99), and 1.78% (95% CI, 1.10-2.46) increase of COPD mortality, respectively. The concentration response curves indicated linear associations without threshold. Only NO2 remained significant in the multi-pollutant models. To our knowledge, this is the first multi-city study in Asian developing region to report the short-term effect of air pollution on COPD mortality. Our results contribute to very limited data on the effects of air pollution on COPD mortality for high exposure settings typical in developing countries. (C) 2013 Elsevier Ltd. All rights reserved.

Abstract  The Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP) consists of a series of time slice experiments targeting the long-term changes in atmospheric composition between 1850 and 2100, with the goal of documenting composition changes and the associated radiative forcing. In this overview paper, we introduce the ACCMIP activity, the various simulations performed (with a requested set of 14) and the associated model output. The 16 ACCMIP models have a wide range of horizontal and vertical resolutions, vertical extent, chemistry schemes and [GRAPHICA] interaction with radiation and clouds. While anthropogenic and biomass burning emissions were specified for all time slices in the ACCMIP protocol, it is found that the natural emissions are responsible for a significant range across models, mostly in the case of ozone precursors. The analysis of selected present-day climate diagnostics (precipitation, temperature, specific humidity and zonal wind) reveals biases consistent with state-of-the-art climate models. The model-to-model comparison of changes in temperature, specific humidity and zonal wind between 1850 and 2000 and between 2000 and 2100 indicates mostly consistent results. However, models that are clear outliers are different enough from the other models to significantly affect their simulation of atmospheric chemistry.

Abstract  National Ambient Air Quality Standards (NAAQS) are promulgated by the United States Environmental Protection Agency (EPA) to meet requirements set forth in Sections 108 and 109 of the U.S. Clean Air Act (CAA). Sections 108 and 109 require the EPA Administrator (1) to list widespread air pollutants that reasonably may be expected to endanger public health or welfare; (2) to issue air quality criteria for them that assess the latest available scientific information on nature and effects of ambient exposure to them; (3) to set primary NAAQS to protect human health with adequate margin of safety and to set secondary NAAQS to protect against welfare effects (e.g., effects on vegetation, ecosystems, visibility, climate, manmade materials, etc); and (5) to periodically review and revise, as appropriate, the criteria and NAAQS for a given listed pollutant or class of pollutants.

Abstract  OBJECTIVE: To determine whether oxidative/nitrosative stress plays a role in the acute effects of diesel exhaust (DE) on subjects with asthma.

METHODS: In this crossover study, 16 subjects with mild to moderate asthma were exposed to clean filtered air or diluted DE (300 μg/m as PM2.5) for 1 hour with intermittent exercise.

RESULTS: Airway hyperreactivity increased 24 hours after exposure to DE compared with clean filtered air (PC20, 14.9 mg/mL vs 19.7 mg/mL; P = 0.012). Nitrite in exhaled breath condensate was elevated immediately after diesel exposure (P = 0.052) and remained elevated 4 and 24 hours after exposure.

CONCLUSIONS: After exposure to DE, subjects with asthma demonstrated increased airway hyperreactivity and obstruction. Increased nitrite in exhaled breath condensate, in the absence of increased exhaled nitric oxide, suggests a noninflammatory oxidative stress mechanism by which DE affects the lung.

Abstract  Twelve mildly asthmatic and four healthy adults were exposed to filtered air (FA) and concentrated ambient coarse particles (CCP) supplied to a whole-body exposure chamber via a coarse particle concentrator with 15 parallel virtual impactors. Exposures were conducted in a Los Angeles suburb with high levels of motor-vehicle pollution and lasted 2 h with intermittent exercise. Mean CCP concentration was 157 microg/m(3) (range: 56-218 microg/m(3)) measured by continuous monitoring with a tapered-element oscillating microbalance (TEOM). On average, 80% of mass was coarse (2.5-10 microm aerodynamic diameter) and the rest <2.5 microm. Relative to FA, CCP exposure did not significantly alter respiratory symptoms, spirometry, arterial oxygen saturation, or airway inflammation according to exhaled nitric oxide and total and differential cell counts of induced sputum. After CCP exposure, Holter electrocardiograms showed small (p <.05) increases in heart rate and decreases in heart-rate variability, which were larger in healthy than in asthmatic subjects. Cardiac ectopy did not increase. In conclusion, acute exposure to elevated concentrations of ambient coarse particles elicited no obvious pulmonary effects but appeared to alter the autonomic nervous system of the heart in adult volunteers.

Abstract  Background: A number of studies have shown associations between chronic exposure to particulate air pollution and increased mortality, particularly from cardiovascular disease, but fewer studies have examined the association between long-term exposure to fine particulate air pollution and specific cardiovascular events, such as acute myocardial infarction (AMI).
 Objective: We examined how long-term exposure to area particulate matter affects the onset of AMI, and we distinguished between area and local pollutants.
 Methods: Building on the Worcester Heart Attack Study, an ongoing community-wide investigation examining changes over time in myocardial infarction incidence in greater Worcester, Massachusetts, we conducted a case–control study of 4,467 confirmed cases of AMI diagnosed between 1995 and 2003 and 9,072 matched controls selected from Massachusetts resident lists. We used a prediction model based on satellite aerosol optical depth (AOD) measurements to generate both exposure to particulate matter ≤ 2.5 μm in diameter (PM2.5) at the area level (10 × 10 km) and the local level (100 m) based on local land use variables. We then examined the association between area and local particulate pollution and occurrence of AMI.
 Results: An interquartile range (IQR) increase in area PM2.5 (0.59 μg/m3) was associated with a 16% increase in the odds of AMI (95% CI: 1.04, 1.29). An IQR increase in total PM2.5 (area + local, 1.05 μg/m3) was weakly associated with a 4% increase in the odds of AMI (95% CI: 0.96, 1.11).
 Conclusions: Residential exposure to PM2.5 may best be represented by a combination of area and local PM2.5, and it is important to consider spatial gradients within a single metropolitan area when examining the relationship between particulate matter exposure and cardiovascular events.


Abstract  BACKGROUND: The prevalence of Autistic Disorder (AD), a serious developmental condition, has risen dramatically over the past two decades but high-quality population-based research addressing etiology is limited. OBJECTIVES: We studied the influence of exposures to traffic-related air pollution during pregnancy on the development of autism using data from air monitoring stations and a land use regression (LUR) model to estimate exposures. METHODS: Children of mothers who gave birth in Los Angeles who were diagnosed with a primary AD diagnosis at ages 3-5 years during 1998-2009 were identified through the California Department of Developmental Services and linked to 1995-2006 California birth certificates. For 7,603 children with autism and 10 controls per case matched by sex, birth year, and minimum gestational age, birth addresses were mapped and linked to the nearest air monitoring station and a LUR model. We used conditional logistic regression, adjusting for maternal and perinatal characteristics including indicators of SES. RESULTS: Per interquartile range (IQR) increase, we estimated a 12-15% relative increase in odds of autism for O3 (OR = 1.12, 95% CI: 1.06, 1.19; per 11.54 ppb increase) and PM2.5 (OR = 1.15, 95% CI: 1.06, 1.24; per 4.68 μg/m3 increase) when mutually adjusting for both pollutants. Furthermore, we estimated 3-9% relative increases in odds per IQR increase for LUR-based NO and NO2 exposure estimates. LUR-based associations were strongest for children of mothers with less than a high school education. CONCLUSION: Measured and estimated exposures from ambient pollutant monitors and LUR model suggest associations between autism and prenatal air pollution exposure, mostly related to traffic sources.

Abstract  The purpose of this work is to better understand the complex behavior of certain important species that affect air quality in general, and haze formation in particular. With funding from LADCO and CENRAP we are monitoring ambient gasphase ammonia, sulfur dioxide and nitric acid, as well as ammonium, sulfate and nitrite in PM?2.5 filter samples collected at selected sites in the Midwest?one each in Iowa, Illinois, Missouri, Kansas, Oklahoma, Kentucky, Ohio and Michigan, and two in Minnesota. Two types of timer?operated field samplers are deployed in this project?the commercially available model 2300 from Ruprecht and Patashnick (R&P), and the ISWS custom?built system, which uses a cyclone (R&P uses an impactor), denuders and filter pack assemby from University Research Glassware (URG). Samples are collected on a rotating one?day?in?six schedule that coincides with other nationwide air monitoring programs. At the Bondville, IL site, ambient ammonia concentrations are also measured every 35 seconds by a Nitrolux?200 photoaccoustic monitor. Samples extracted from denuders and filters are analyzed in the National Atmospheric Deposition Program?s Central Analytical Laboratory using ion chromatography and flow injection analysis under strict quality control. Data from this project will facilitate computer simulations of the possible effects of emissions controls, and other scenarios of environmental interest.

Abstract  Estimates of carbon uptake and storage based on global nitrogen deposition, C:N ratios for typical terrestrial ecosystems, and recent ecosystem-scale nutrient studies indicate that 1.0-2.3 Gt C yr-1 of carbon storage may be stimulated by anthropogenically caused increases in nitrogen deposition in the past century. Sixty four to eighty four percent of global nitrogen uptake appears to occur on northern continents, with the remainder largely in northern coastal oceans. Increased nitrogen input by terrestrial ecosystems causes increased accumulation of carbon as plant tissue, with C:N ratios generally 50 to 200:1. Calculations suggest that northern continents are a major sink for carbon and that nitrogen-stimulated carbon uptake may more or less balance global carbon losses to the atmosphere from deforestation and agriculture. Much of the uptake appears to occur in aggrading forests, and the question of how long it can continue has important consequences for global carbon budgets.

Abstract  Short-term effects of air pollution on common morbidity are largely unknown. The authors explored links between daily levels of air pollution (nitrogen dioxide, ozone, and particulate matter less than 10 lm in diameter (PM10)) and medical home visits made for diverse reasons in Bordeaux, France, during 2000–2006. Daily numbers of visits were obtained from a network of general practitioners. The excess relative risk (ERR) of a visit for each indicator associated with increased pollutant levels was estimated by fitting a Poisson regression model, controlling for well known confounding factors and temporal trends. Positive and significant associations were found between air pollution and most health indicators. A 10-lg/m3 increase in PM10 levels was associated with increases in visits for upper and lower respiratory diseases (ERRs were 1.5% (95% confidence interval (CI): 0.3, 2.7) and 2.5% (95% CI: 0.5, 4.4), respectively), headache and asthenia (ERR = 3.5%, 95% CI: 1.3, 5.9), and skin rash and conjunctivitis (ERR= 3.2%, 95% CI: -0.2, 6.8). Significant associations were also found between nitrogen dioxide and ozone and several health indicators. Distributed-lag models showed no harvesting effect, and some effects persisted up to 15 days after exposure increased. These results suggest that considering only the most severe effects of air pollution leads to underestimation of its impact on public health.

Abstract  BACKGROUND: The association of long-term air pollution and lung function has not been studied across adult European multi-national populations before. The aim of this study was to determine the association between long-term urban background air pollution and lung function levels, as well as change in lung function among European adults. METHODS:Forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC) and the ratio thereof (FEV1/FVC) were assessed at baseline and after 9 years of follow-up in adults from 21 European centres (followed-up sample 5610). Fine particles (PM(2.5)) were measured in 2000/2001 using central monitors. RESULTS: Despite sufficient statistical power no significant associations were found between city-specific annual mean PM(2.5) and average lung function levels. The findings also do not support an effect on change in lung function, albeit statistical power was insufficient to significantly detect such an association. CONCLUSIONS: The inability to refuse the null hypothesis may reflect (i) no effect of urban air pollution on lung function or (ii) inherent biases due to the study design. Examples of the latter are lack of individual-level air quality assignment, not quantified within-city contrasts in traffic-related pollution, or the heterogeneity of the studied populations and their urban environments. Future studies on long-term effects of air pollution on lung function could increase statistical power and reduce potential misclassification and confounding by characterizing exposure on the level of individuals, capturing contrasts due to local sources, in particular traffic.

Abstract  BACKGROUND: Recent studies indicate that the composition of fine particulate matter [PM ≤ 2.5 μm in aerodynamic diameter (PM2.5)] is associated with increased hospitalizations for cardiovascular and respiratory diseases. The metal composition of PM2.5 influences allergic and/or inflammatory reactions, and ambient zinc contributes to worsening pulmonary function in susceptible adults. However, information is limited concerning associations between ambient air zinc levels and health care utilization for asthma, especially among children. OBJECTIVE: We aimed to investigate the relationship between outdoor ambient air PM2.5 zinc levels and urgent health care utilization for children living in an urban area. METHODS: We used a time-series study to estimate the association of ambient air PM2.5 zinc levels with hospital admissions and emergency department (ED) utilization by children in Baltimore, Maryland, controlling for time trends. We used data from daily discharge administrative claims of ED and hospital utilization for asthma in children, 0–17 years of age for Greater Baltimore from June 2002 through November 2002. We collected ambient air PM2.5 metal concentration data, determined by X-ray fluorescence spectroscopy, during the U.S. Environmental Protection Agency–sponsored Baltimore Supersite project. RESULTS: Previous-day medium levels of zinc (8.63–20.76 ng/m3) are associated with risks of pediatric asthma exacerbations that are 1.23 (95% confidence interval, 1.07–1.41) times higher than those with previous-day low levels of zinc (< 8.63 ng/m3) after accounting for time-varying potential confounders. CONCLUSION: Results suggest that high ambient air PM2.5 zinc levels are associated with an increase in ED visits/hospital admissions for asthma on the following day among children living in an urban area.

Abstract  Objective: The prevalence of adverse respiratory outcomes among children has been frequently associated with measurements of traffic-related exposures, and other data suggest asthma severity is worsened with residence near heavy traffic. We examined the association between neighbourhood traffic burden and repeated acute respiratory illnesses that required emergency department visits and/or hospitalisation for children with a primary or secondary diagnosis of asthma (89% acute bronchitis or pneumonia). Methods: This is a hospital-based longitudinal study of a southern California urban catchment area around two adjacent children’s hospitals. Subjects’ home addresses were geocoded and linked to nearby traffic data. Recurrent event proportional hazard analysis was used to estimate the hazard of repeated hospital encounters. Results: We found living within 300 metres of arterialroads or freeways increased risk of repeated hospital encounters in 3297 children age 18 years or less. At highest risk were children in the top quintile of traffic density (HR=1.21; 95% CL 0.99 to 1.49) and those who had 750 metres or more of arterial road and freeway length within 300 metres of their residence (HR=1.18; 95% CL 0.99 to 1.41). Associations between repeated hospital encounters and residence near heavy traffic were stronger in females than males and in children without insurance or who required government sponsored insurance than children with private insurance. The gender disparity was most notable among infants (age 0) and children ages 6–18 years. Conclusions: Results suggest exposure to traffic-related air pollution increases asthma severity as indicated by hospital utilisation. The finding in infants suggests this is an especially vulnerable population, although the validity of asthma diagnosis at this age is unknown. Females and children who do not have private insurance may also be more vulnerable to air pollution from traffic.

Abstract  A radiative transfer scheme that considers absorption, scattering, and distribution of light-absorbing elemental carbon (EC) particles collected on a quartz-fiber filter was developed to explain simultaneous filter reflectance and transmittance observations prior to and during thermal/optical analysis for carbonaceous aerosol. The model is applied to study ambient filter samples from the United States and HongKong, China, and how they differ from each other and from reference carbon black samples. Most particles in ambient samples deposit into the top half of the filter, resuspended carbon black particles are only found close to the filter surface. Pyrolized/charred organic carbon (POC) generated during thermal analysis reduces filter reflectance and transmittance in a fashion that suggests a uniform distribution of POC throughout the filter. When heated in oxygen, most EC evolves earlier than the within-filter charring for certain ambient samples. This shows the different natures of EC, and also results in an inexact optical correction to separate organic and elemental carbon by thermal analysis, especially when the POC/EC ratio is large. Particle absorption in the filter is estimated for comparisons with the EC/POC measurements, suggesting a mass absorption eDciency of ~2.7 ± 0.2 m2 (gC)?1 for reference carbon black and >15 m2 (gC)?1 for ambient EC, similar to previous estimates in the literature.

Abstract  Aerosol mass spectrometry has become an essential tool in monitoring tropospheric aerosols. Various approaches have been developed for analyzing particles that range in size from 10 nm to 10 ?m in diameter, and which consist of salts, soot, crustal matter, metals, and organic molecules, often mixed together. This wide variety of particle types has generated an equally wide variety of ionization sources, which include electron impact, laser ionization, laser desorption, chemical ionization, and electron capture ionization. Some instruments are capable of single particle analysis, while others require the collection of an ensemble of particles to obtain sufficient sample for analysis. Most instruments have been designed to ionize and analyze particular classes of compounds (e.g. salts, soot, or organics). This review provides a very broad overview of the aerosol mass spectrometry field and serves as an introduction to the many papers in this issue that deal with details about specific instruments.

Abstract  OBJECTIVE: Air pollution can promote airway inflammation, posing significant health risks for children with chronic respiratory problems. However, it is unknown whether this process is reversible, so that limiting pollution will benefit these children. We measured the short-term response of allergic asthmatic children exposed to a real-life reduction in outdoor air pollution by using noninvasive biomarkers of airway inflammation and function. PATIENTS AND METHODS: Thirty-seven untreated allergic children with mild persistent asthma were recruited from a highly polluted urban environment and relocated to a less polluted rural environment. Air pollution, pollen counts, and meteorological conditions were carefully monitored at both sites. Nasal eosinophils, fractional exhaled nitric oxide, peak expiratory flow, and urinary leukotriene E(4) were measured first in the urban environment and then again 7 days after relocation to the rural environment. RESULTS: One week after relocation to the rural environment, we measured, on average, a fourfold decrease in nasal eosinophils and significant decrease in fractional exhaled nitric oxide. We also noted an improvement in lower airway function, reflected by highly significant increase in peak expiratory flow. In contrast, mean urinary leukotriene E(4) concentration remained unchanged after 1 week of exposure to the rural environment. CONCLUSIONS: Better air quality is associated with a rapid reduction of airway inflammation in allergic asthmatic children. Nasal eosinophils and fractional exhaled nitric oxide are sensitive indicators of this effect, and their rapid decline is paralleled by improved airway function measured by peak expiratory flow. Leukotriene synthesis has a more variable response to environmental modifications.

Abstract  A parameterization of aerosol optical parameters is developed and implemented in an extended version of the community climate model version 3.2 (CCM3) of the U.S. National Center for Atmospheric Research. Direct radiative forcing (DRF) by monthly averaged calculated concentrations of non-sea-salt sulfate and black carbon (BC) is estimated. Inputs are production-specific BC and sulfate from Iversen and Seland [2002] and background aerosol size distribution and composition. The scheme interpolates between tabulated values to obtain the aerosol single scattering albedo, asymmetry factor, extinction coefficient, and specific extinction coefficient. The tables are constructed by full calculations of optical properties for an array of aerosol input values, for which size-distributed aerosol properties are estimated from theory for condensation and Brownian coagulation, assumed distribution of cloud-droplet residuals from aqueous phase oxidation, and prescribed properties of the background aerosols. Humidity swelling is estimated from the Köhler equation, and Mie calculations finally yield spectrally resolved aerosol optical parameters for 13 solar bands. The scheme is shown to give excellent agreement with nonparameterized DRF calculations for a wide range of situations. Using IPCC emission scenarios for the years 2000 and 2100, calculations with an atmospheric global cliamte model (AFCM) yield a global net anthropogenic DRF of −0.11 and 0.11 W m−2, respectively, when 90% of BC from biomass burning is assumed anthropogenic. In the 2000 scenario, the individual DRF due to sulfate and BC has separately been estimated to −0.29 and 0.19 W m−2, respectively. Our estimates of DRF by BC per BC mass burden are lower than earlier published estimates. Some sensitivity tests are included to investigate to what extent uncertain assumptions may influence these results.

Abstract  The indirect effect of anthropogenic aerosols, whereby aerosol particles change cloud optical properties, is the most uncertain component of climate forcing over the past 100 years. Here we use a mechanistic treatment of droplet nucleation and a prognostic treatment of the number of cloud droplets to study the indirect aerosol effect from changes in carbonaceous and sulfate aerosols. Cloud droplet nucleation is parameterized as a function of total aerosol number concentration, updraft velocity, and an activation parameter, which takes into account the mechanism of sulfate aerosol formation. Where previous studies focussed either on sulfate aerosols or carbonaceous aerosols only, here we estimate the combined effect. The combined indirect aerosol effect amounts to −1.1 W m−2 for an internally mixed aerosol and −1.5 W m−2 for an externally mixed aerosol compared to −1.4 W m−2, which we obtained by empirically relating sulfate mass to cloud droplet number. In the case of an internally mixed aerosol, the contribution from increasing carbonaceous and sulfate aerosols is close to being additive as the individual simulations yield an indirect effect of −0.4 W m−2 due to anthropogenic sulfate aerosols and −0.9 W m−2 due to anthropogenic carbonaceous aerosols. The contribution of anthropogenic sulfate to the indirect effect is close to zero if an externally mixed aerosol is assumed, while the contribution of carbonaceous aerosols increases to −1.3 W m−2. The effect of sulfate in the external mixture approach is much smaller than that of carbonaceous aerosols because its burden only increases by a third of that of carbonaceous aerosols and because the mode radius of sulfate is much larger than that of black and organic carbon.

Abstract  A variety of measurements have been used to evaluate the treatment of aerosol radiative properties and radiative impacts of aerosols simulated by the Model for Integrated Research on Atmospheric Global Exchange (MIRAGE). The treatment of water uptake in MIRAGE agrees with laboratory measurements, and the growth of aerosol extinction with relative humidity in MIRAGE simulations agrees with field measurements. The simulated frequency of relative humidity near 100% is about twice that of analyzed relative humidity. When the analyzed relative humidity is used to calculate aerosol water uptake in MIRAGE, the simulated aerosol optical depth agrees with most surface measurements after cloudy conditions are filtered out and differences between model and station elevations are accounted for, but simulated optical depths are too low over Brazil and central Canada. Simulated optical depths are mostly within a factor of 2 of satellite estimates, but are too high off the east coasts of the United States and China and too low off the coast of West Africa and in the Arabian Sea. The simulated single-scatter albedo is consistent with surface measurements. MIRAGE correctly simulates a larger Ångström exponent near regions with emissions of submicron particles and aerosol precursor gases, and a smaller exponent near regions with emissions of coarse particles. The simulated sensitivity of radiative forcing to aerosol optical depth is consistent with estimates from measurements. The simulated direct forcing is within the uncertainty of estimates from measurements in the North Atlantic.

Abstract  Emissions from fossil fuel combustion and biomass burning reduce local air quality and affect global tropospheric chemistry. Nitrogen oxides are emitted by all combustion processes and play a key part in the photochemically induced catalytic production of ozone, which results in summer smog and has increased levels of tropospheric ozone globally. Release of nitrogen oxide also results in nitric acid deposition, and--at least locally--increases radiative forcing effects due to the absorption of downward propagating visible light. Nitrogen oxide concentrations in many industrialized countries are expected to decrease, but rapid economic development has the potential to increase significantly the emissions of nitrogen oxides in parts of Asia. Here we present the tropospheric column amounts of nitrogen dioxide retrieved from two satellite instruments GOME and SCIAMACHY over the years 1996-2004. We find substantial reductions in nitrogen dioxide concentrations over some areas of Europe and the USA, but a highly significant increase of about 50 per cent-with an accelerating trend in annual growth rate-over the industrial areas of China, more than recent bottom-up inventories suggest.

Abstract  Assessing the effects of air quality on public health and the environment requires reliable measurement of PM2.5 mass and its chemical components. This study seeks to evaluate PM2.5 measurements that are part of a newly established national network by comparing them with more versatile sampling systems. Experiments were carried out during 2002 at a suburban site in Maryland, United States, where two samplers from the US Environmental Protection Agency (US EPA) Speciation Trends Network: Met One Speciation Air Sampling System-STNS and Thermo Scientific Reference Ambient Air Sampler-STNR, two Desert Research Institute Sequential Filter Samplers-DRIF, and a continuous TEOM monitor (Thermo Scientific Tapered Element Oscillating Microbalance, 1400a) sampled air in parallel. These monitors differ not only in sampling configuration but also in protocol-specific laboratory analysis procedures. Measurements of PM2.5 mass and major contributing species (i.e., sulfate, ammonium, organic carbon, and total carbon) were well correlated among the different methods with r-values >0.8. Despite the good correlations, daily concentrations of PM2.5 mass and major contributing species were significantly different at the 95% confidence level from 5% to 100% of the time. Larger values of PM2.5 mass and individual species were generally reported from STNR and STNS. These differences can only be partially accounted for by known random errors. Variations in flow design, face velocity, and sampling artifacts possibly influenced the measurement of PM2.5 speciation and mass closure. Statistical tests indicate that the current uncertainty estimates used in the STN and DRI network may underestimate the actual uncertainty.

Abstract  Objective: The estimated mortality rate associated with ambient air pollution based on general population studies may not be representative of the effects on certain subgroups. The objective of the present study was to determine the influence of relatively high concentrations of air pollution on mortality in a general population sample and in the very elderly. Study design: Daily time-series analyses tested the association between daily air pollution and daily mortality in seven Chilean urban centers during 1997-2003. Results were adjusted for day of the week and humidex. Results: Daily averaged particulate matter with aerodynamic matter < 10 Ám (PM10) was 84.88 Ág/m3, sulfur dioxide was 14.08ppb, and carbon monoxide was 1.29 ppb. The 1-hr maximum ozone was 100.13 ppb. The percentage increases in nonaccidental mortality associated with an increase in PM10 equivalent to its mean were 4.53 (t-ratio 1.52) for those < 65 years and 14.03 (3.87) for those > 85 years. Respective values were 4.96 (1.17) and 8.56 (2.02) for O3 ; 4.77 (2.50) and 7.92 (3.23) for SO2 ; and 4.10 (2.52) and 8.58 (4.45) for CO. Conclusion: Our results suggest that the very elderly are particularly susceptible to dying from air pollution. Concentrations deemed acceptable for the general population may not adequately protect the very elderly.

Abstract  Background and Purpose--Daily variation in outdoor concentrations of inhalable particles (PM10 <10 Ám in diameter) has been associated with fatal and nonfatal stroke. Toxicological and epidemiological studies suggest that smaller, combustion-related particles are especially harmful. We therefore evaluated the effects of several particle measures including, for the first time to our knowledge, ultrafine particles (<0.1 Ám) on stroke. Methods--Levels of particulate and gaseous air pollution were measured in 1998 to 2004 at central outdoor monitoring sites in Helsinki. Associations between daily levels of air pollutants and deaths caused by stroke among persons aged 65 years or older were evaluated in warm and cold seasons using Poisson regression. Results--There was a total of 1304 and 1961 deaths from stroke in warm and cold seasons, respectively. During the warm season, there were positive associations of stroke mortality with current- and previous-day levels of fine particles (<2.5 Ám, PM2.5) (6.9%; 95% CI, 0.8% to 13.8%; and 7.4%; 95% CI, 1.3% to 13.8% for an interquartile increase in PM2.5) and previous-day levels of ultrafine particles (8.5%; 95% CI, -1.2% to 19.1%) and carbon monoxide (8.3; 95% CI, 0.6 to 16.6). Associations for fine particles were mostly independent of other pollutants. There were no associations in the cold season. Conclusions--Our results suggest that especially PM2.5, but also ultrafine particles and carbon monoxide, are associated with increased risk of fatal stroke, but only during the warm season. The effect of season might be attributable to seasonal differences in exposure or air pollution mixture.

Abstract  OBJECTIVE: Several studies have examined the effect of particulate pollution (PM) on survival in general populations, but less is known about susceptible groups. Moreover, previous cohort studies have been cross-sectional and subject to confounding by uncontrolled differences between cities. DESIGN: We investigated whether PM was associated with progression of disease or reduced survival in a study of 196,000 persons from 21 U.S. cities discharged alive following an acute myocardial infarction (MI), using within-city between-year exposure to PM. We constructed city-specific cohorts of survivors of acute MI using Medicare data between 1985 and 1999, and defined three outcomes on follow-up: death, subsequent MI, and a first admission for congestive heart failure (CHF). Yearly averages of PM(10) (particulate matter with aerodynamic diameter < 10 microm) were merged to the individual annual follow-up in each city. We applied Cox's proportional hazard regression model in each city, with adjustment for individual risk factors. In the second stage of the analysis, the city-specific results were combined using a meta-regression. RESULTS: We found significant associations with a hazard ratio for the sum of the distributed lags of 1.3 [95% confidence interval (CI), 1.2-1.5] for mortality, a hazard ratio of 1.4 (95% CI, 1.2-1.7) for a hospitalization for CHF, and a hazard ratio of 1.4 (95% CI, 1.1-1.8) for a new hospitalization for MI per 10 microg/m(3) PM(10). CONCLUSIONS: This is the first long-term study showing a significant association between particle exposure and adverse post-MI outcomes in persons who survived an MI.